---
title: "Changes to Create a model response"
method: POST
path: "/responses?beta=true"
---

# Changes to Create a model response

`POST /responses?beta=true`

> Every recorded change to this endpoint, newest first.

## Timeline

Changed in 4 of 31 revisions.

- **2026-07-30** `26e845904dd2` — 7 warning, 1 info
- **2026-07-23** `0514a733c82d` — 21 breaking, 7 warning, 2 info
- **2026-07-17** `241fb501b372` — 3 breaking, 7 info
- **2026-07-09** `e0508a503b84` — 1 info

## Changes

- **2026-07-30** `26e845904dd2` — 7 warning, 1 info
  - added the new `fast` enum value to the `allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: application/json)
  - added the new `fast` enum value to the `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/` response property for the response status `200` (media type: text/event-stream)
  - added the new `fast` enum value to the request property `allOf[#/components/schemas/BetaCreateModelResponseProperties]/allOf[#/components/schemas/BetaModelResponseProperties]/service_tier/anyOf[subschema #1]/`
- **2026-07-23** `0514a733c82d` — 21 breaking, 7 warning, 2 info
  - response property `allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `application/json` of response `200`
  - response property `allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `application/json` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - response property `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `text/event-stream` of response `200`
  - the `allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: application/json)
  - the `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - the `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - the `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - the `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - the `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - the `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` response property's maxLength was unset from `64` for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: application/json)
  - added the new `data_residency_mismatch` enum value to the `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - added the new `data_residency_mismatch` enum value to the `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[subschema #3]/error/anyOf[subschema #1]/code` response property for the response status `200` (media type: text/event-stream)
  - request property `allOf[#/components/schemas/BetaCreateModelResponseProperties]/allOf[#/components/schemas/BetaModelResponseProperties]/prompt_cache_key` list-of-types was widened by adding types `null` to media type `application/json`
  - request property `allOf[#/components/schemas/BetaCreateModelResponseProperties]/allOf[#/components/schemas/BetaModelResponseProperties]/safety_identifier` list-of-types was widened by adding types `null` to media type `application/json`
- **2026-07-17** `241fb501b372` — 3 breaking, 7 info
  - removed `subschema #1, subschema #2, subschema #3` from the `allOf[subschema #3]/input/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` request property `anyOf` list
  - the `allOf[subschema #3]/input/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` request property type/format changed from ``/`` to `array`/``
  - the `allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response's property type/format changed from ``/`` to `array`/`` for status `200` (media type: application/json)
  - removed `subschema #1, subschema #2, subschema #3` from the `allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: application/json)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[#/components/schemas/BetaResponseCompletedEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[#/components/schemas/BetaResponseCreatedEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[#/components/schemas/BetaResponseFailedEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[#/components/schemas/BetaResponseInProgressEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[#/components/schemas/BetaResponseIncompleteEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
  - removed `subschema #1, subschema #2, subschema #3` from the `anyOf[subschema #51: ResponseQueuedEvent]/response/allOf[subschema #3]/instructions/anyOf[subschema #1]/anyOf[subschema #2: Input item list]/items/anyOf[subschema #2: Item]/anyOf[#/components/schemas/BetaMultiAgentCallOutputItemParam]/output/items/annotations` response property `anyOf` list for the response status `200` (media type: text/event-stream)
- **2026-07-09** `e0508a503b84` — 1 info
  - endpoint added

---

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